Questions tagged [concrete]

Concrete is composed of cement, aggregate (including crushed rock and sand) and water. In homes, it's frequently seen in the foundation, driveway, sidewalk, patio, and stone walls. Note that bricks use mortar in the joints, not concrete.

Filter by
Sorted by
Tagged with
33
votes
11answers
12k views

Is this cracking foundation under a jack post a problem that requires repair?

I am buying an already-built new home. I find this in the basement. The builder says it's okay, but I am really concerned. Is this really a big issue? What steps would be required to repair it? This ...
28
votes
7answers
22k views

Pouring concrete, is it safe to add large rocks to increase volume?

Backround I'm going to pour some concrete to anchor a swing set. The base of the swing set that is being anchored is two 4x4s with a 2x4 footer crossed perpendicularly to the 4x4s. I have a bunch of ...
21
votes
1answer
29k views

Are cracks in a newly poured concrete basement floor a problem?

I'm having a new home built and found a large crack in the newly poured concrete basement floor and wanted to see if it's something I should be concerned about. The floor was poured sometime in the ...
19
votes
1answer
6k views

How to add on to a concrete patio?

I would like to add on to my existing concrete patio with more concrete. I will about double the size of the patio. My question is, should I have the new patio free floating from the existing or ...
18
votes
3answers
3k views

What happens to foam insulation board after you pour concrete slab?

I plan on making a garage out of a large carport, and I've watched and I understood how to properly insulate a new concrete slab. 4 inches of gravel, vapor barrier, 2 inch foam board, 2 inches of sand ...
15
votes
5answers
67k views

Why do builders say that wet concrete/mortar is not as strong?

I have been watching a few videos demonstrating the mixing of mortar and cement and a constant theme is that you must not have the mix too runny. I cannot fathom the reason... Does anyone care to ...
14
votes
11answers
4k views

Knowing where to drill holes in steel plate?

I have a concrete floor and I made two holes to bolt a 1/4"-thick steel plate. The problem is that the steel plates haven't been drilled yet. How can I determine where the holes will be drilled in ...
13
votes
10answers
117k views

Do I have to remove the old thinset before installing new tile?

I will be installing some new 12x12 tiles in two bathrooms approx 25 sq/ft each. When I pulled up the old tiles, there was no thin set that had made contact with them so the removal was very easy. Now,...
13
votes
9answers
35k views

Should I set wood fence posts in quikrete with no supplemental water?

Setting wood fence post---I've heard to set wood fence posts using quikrete dry, allowing it get moisture from the ground. Is this a good idea?
13
votes
6answers
16k views

Should gloves be worn when working with concrete to prevent it from coming in contact with skin?

I was told recently that concrete is slightly corrosive. Should gloves be worn when using concrete or is it fine to handle concrete as long as its not done on a regular basis?
13
votes
2answers
3k views

Is a roofing delivery truck likely to crack my driveway slab?

I am having shingles delivered. The truck weighs 62,000 lbs, will this crack my concrete slab driveway? Also, they plan on a dump truck in the driveway to throw shingles from the roof. I am not sure ...
13
votes
2answers
3k views

Can I build a concrete block wall over floor tile?

I am enclosing a tiled porch on concrete slab with a 3' short wall of concrete block, with windows above. Should concrete blocks be laid over a tile floor?
12
votes
11answers
5k views

awkward driveway curve has cars nearly colliding with house, how to mitigate? [closed]

Bellow is an arial photo and a road-side photo of my new house. As you can see the driveway is an awkward curve especially when backing out of the car port to the side of the garage - you have to do ...
12
votes
4answers
143k views

How do you secure wood framing to a concrete basement floor?

I'm using Pressure treated lumber for the bottom plate in a basement finishing project. What should I use to seperate the wood from the concrete? What are ways to secure the bottom plate to the floor?...
11
votes
3answers
42k views

Driveway expansion joints are rotting wood: What to replace the wood?

My driveway was poured in sections with lengths of 2x4 which remained between the slabs as expansion joints. Due to heaving and moisture many of these are in poor shape. I replaced one once by ...
11
votes
5answers
24k views

Can I mix latex paint into concrete

would like to color concrete mix can I use outdoor latex paint to mix in with the concrete?
11
votes
6answers
6k views

re-using wood from a concrete form?

I strive to not waste materials wherever possible, and "use once then discard" methods are particularily irksome. So with this mind, what suggestions do you have for enabling re-use of lumber used for ...
11
votes
1answer
3k views

How do I build a form and pour a concrete pad?

I have a new safe that I want to put out in the garage. I'd like for it to be in a specific corner, but that corner has a few quirks. First, the slab is pretensioned. No cutting, drilling, coring, ...
11
votes
1answer
10k views

Is it OK to pave without mixing?

Going upon the advice of a reputable builder, I used Quikrete fast-drying concrete for a small slab outside my house. Not load bearing. His recommendation was to dry-pour the whole thing. Framed, ...
10
votes
9answers
8k views

How can I pour a concrete pad with a circular hole in it?

Essentially, I'd like to put down a concrete pad for a patio, but leave a couple of circular areas within that patio unpaved (for planting shrubs). I'm familiar with the techniques for using ...
10
votes
3answers
7k views

Why are there metal tabs protruding from my poured concrete foundation walls?

What are these metal things sticking out from my basement walls? Can they be removed? If so, how?
10
votes
3answers
73k views

How do I remove THIN layer of carpet glue from concrete?

The folks who owned this house before us were the cheapest people around. They glued carpet to our concrete floor with a very thin layer of glue. Now, I'm having a terrible time scraping it off. I ...
10
votes
1answer
243 views

In a house fire, how hot does the foundation have to get before it too has to be replaced?

Not long after the Oakland Hills fire in the early 90's I was talking with a homeowner. I ignorantly said that at least he can still rebuild on the same foundation. He said that at about 2,000°F the ...
10
votes
3answers
12k views

How do I fill in around waste pipes?

Broke the concrete in my basement to run new pipes for the basement bathroom. The plumber put sand under the pipes to support them at the correct angle. I asked him not to glue the vertical sections ...
10
votes
1answer
3k views

Foundation for structure on bedrock

We have the mixed blessing of a giant swath of exposed Canadian Shield on our property in Ontario. Literally a big flat area of exposed rock, no soil whatsoever. Scale is hard to see, but a ...
9
votes
2answers
19k views

How can I level my basement floor, which has a 4-inch dip?

I googled today on how to level a basement floor. Most people recommend using SLC (self leveling concrete)... I don't think I can just use that because of the pitch of my floor (and from what I hear, ...
9
votes
8answers
16k views

Can I hang a heavy weight from a concrete ceiling if I reinforce it with fiberglass?

I'm investigating the possibility of hanging a pull-up bar/ rock-climbing training board from the concrete ceiling in my apartment. The slab is 180mm (7inches) thick and the (static) weight which I ...
9
votes
6answers
70k views

How much concrete for a fence post?

We're going to build up a 4' fence around our property sometime in here in the spring or summer with 4x4 posts. I've seen that you should bury 1/3 to 1/2 of the above ground post height; so this ...
9
votes
3answers
64k views

How can I prepare uneven concrete basement floor for vinyl planks?

I have roughly 600 sq ft of basement that needs new flooring after some unfortunate flooding this past summer. We had carpet over concrete and are now looking to lay vinyl planks down. There is about ...
9
votes
3answers
4k views

Drilling holes in concrete

I'm not what you'd call a handy guy, and now wife wants me to put up curtains. This task is reduced primarily to getting a bit of metal stuck to the ceiling. I bought screws and anchors. The anchors ...
9
votes
2answers
29k views

Is it safe to drill small holes in load-bearing concrete beams for expansion bolts?

It seems to be very common to drill small holes in any kind of structural concrete for mounting fixtures without worrying too much about any kind of reduction in strength of the structure, but I ...
8
votes
11answers
79k views

Would wrapping a wood fence post in plastic help protect it?

I'm geting ready to install a couple new wooden privacy fence gates on the sides of our house. One of my co-workers suggested to wrap the 4"x4" with plastic stretch wrap around the 2' part that will ...
8
votes
4answers
299 views

1960s bomb shelter a safe place to wait out a tornado?

I have a 1960s 10x12x8 ft concrete room. It was built under our concrete kitchen floor which is at ground level in 1963. The concrete is 12" thick, except for the ceiling which would be about 24" ...
8
votes
1answer
945 views

What are these metal tags attached to my poured concrete basement wall?

What are these metal pieces attached to my basement poured concrete walls? They are about 2x2 with holes and were pressed into some kind of goop. These walls were poured in 1979. Can I remove them?
8
votes
3answers
13k views

How can I color concrete?

I'm going to be using a mold to pour a concrete pathway and I was wondering about coloring options. I've done this previously with this quikrete product. It worked and turned out okay, but one bottle ...
8
votes
2answers
25k views

6in vs 4.5in of concrete for driveway

We need to get our cracked concrete driveway replaced. The damage seems to be a result of tree roots, and the tree has has been removed. Many people who we've spoken to say the concrete should be ...
8
votes
1answer
3k views

How can I get the 2-part epoxy smell out of concrete?

Six months ago or more, my friend used a 2-part epoxy (no longer have the packaging, but it's a double-syringe with clear liquids, purchased at Home Hardware) on something, and some of it (one or both ...
8
votes
1answer
181 views

Flooding In New Construction Building

This weekend, water was observed flowing up, through the floor and through other joints, into the building - making a swimming pool we didn't ask for! Some Background We currently have a project ...
8
votes
1answer
10k views

What drainage should I install under concrete slab in garage?

I have a concrete garage which is halfway inside the hill. Essentially the surface behind the garage is at garage's roof level. Garage's floor is concrete slab 3"-4" thick (at least it's best I could ...
8
votes
3answers
2k views

Concrete countertops ghosting fix?

I just poured my very first concrete project over the weekend and made what I think is a rookie mistake. Somehow I have ghosting from the metal wire that I used as reinforcement. As you can see here:...
7
votes
3answers
5k views

Pure concrete hollow cylinder

My intention is to build a hollow concrete cylinder for a fire pit like this: There are a few people who have done this by using steel sheets bent in to shape with supports between, but I would ...
7
votes
3answers
11k views

What is the best way to fill a 3 inch gap under my concrete front porch?

I'm in need of some help with my concrete foundation. As I was leaving the house this morning I discovered two or three skunks crawling into a gap under my porch. The hole is on the bottom of the ...
7
votes
2answers
2k views

Can old concrete fragments be cleaned and used as crushed stone?

Suppose I need to replace old concrete on a driveway or in any similar scenario. The usual way is to just gather all the old concrete and dispose it to a landfill, then buy cement, sand and crushed ...
7
votes
3answers
13k views

How can I make these concrete columns?

I want to make a narrow concrete, decorative column like the ones found in this garden.. What is used as a mold for these types of columns? What gives the concrete those subtle color changes (the ...
7
votes
1answer
84k views

What is the difference between building sand and plaster sand

Recently I mixed a batch of mortar for building and was unsure if the hardware provided me with building sand or plaster sand.. What are the properties that differentiate the two? and are there any ...
7
votes
3answers
2k views

How can I hang a large but light poster on a concrete pillar?

I have a large (est. 5'x7') sheet of plastic foam with a poster printed on it. It weighs maybe 3 lb and is reasonably stiff. I'd like to hang it on a solid rectangular concrete pillar about 2' wide. ...
7
votes
6answers
22k views

How do I hang shelves on poor quality brick/concrete walls?

I'm trying to install some shelves in my apartment (brick/concrete) but when I drill holes the walls almost seem like they're made of sand. I'm not able to securely fix the screws (I'm using wall ...
7
votes
2answers
63k views

Should I use self-leveling concrete or mortar to level a patched area of concrete prior to tiling it?

I had to repair cast iron pipe in the basement. This left me with a 2ft x 3ft hole in my tiled basement floor. We cut along the grout lines, so I just need to replace the tile and concrete. Well, ...
7
votes
4answers
2k views

How can I attach normal framed walls in between concrete columns?

I'd like to add partitions to this grid of columns. I want to make "normal" walls, framed with 2x4 and faced with plywood or drywall. My concern is how to attach the walls to the columns. Naively, I ...
7
votes
1answer
3k views

What are “concretors' nippers” for?

I came across this tool called "concretors' nippers" I guess they are for some operations with concrete reinforcement, but can't find any details. What operations is this tool for specifically? ...